diff --git a/README.md b/README.md
index 73beeb9..f0e1943 100644
--- a/README.md
+++ b/README.md
@@ -3,3 +3,5 @@
 Wiki、创作站和 Python 导出工具。
 
 详见 [项目结构与运行方式](docs/monorepo.md)。
+
+业务接口详见 [API 说明](docs/api.md)，线上纯文本目录为 `/api?agent_mode=True`。
diff --git a/apps/studio/src/lib/api-documentation.ts b/apps/studio/src/lib/api-documentation.ts
new file mode 100644
index 0000000..8be2f43
--- /dev/null
+++ b/apps/studio/src/lib/api-documentation.ts
@@ -0,0 +1,11 @@
+import type {NextApiRequest,NextApiResponse} from 'next';
+const docs:Record<string,string>={
+ '/studio/api/export/{slug}': '# 导出创作方案\n\n方法：GET\n路径参数：slug，创作方案的稳定标识。\n查询参数：format=markdown 返回 Markdown；其他值或省略时返回带 version:1 的方案 JSON，带附件文件名。\n示例：GET /studio/api/export/{slug}\n错误：404 方案不存在；405 方法不支持。',
+ '/studio/api/health': '# 创作站健康检查\n\n方法：GET, HEAD\n无业务参数。GET 返回 200 JSON：{"status":"ok","service":"prompt-studio"}；HEAD 无正文。\n示例：GET /studio/api/health\n错误：405 方法不支持。',
+};
+export function serveApiDocumentation(req:NextApiRequest,res:NextApiResponse,path:string){
+ if(!['GET','HEAD'].includes(req.method||'')||typeof req.query.agent_mode!=='string'||req.query.agent_mode.toLowerCase()!=='true')return false;
+ if(!docs[path])return false;
+ res.setHeader('Content-Type','text/plain; charset=utf-8');res.setHeader('Cache-Control','no-store');res.status(200);
+ if(req.method==='HEAD')res.end();else res.send(docs[path]+'\n\n使用 GET 或 HEAD，在原地址加 ?agent_mode=True；已有参数时加 &agent_mode=True。值不区分大小写。动态路径可保留占位符读取说明。业务调用请移除 agent_mode。\nAPI 目录：/api?agent_mode=True\n');return true;
+}
diff --git a/apps/studio/src/pages/api/export/[slug].ts b/apps/studio/src/pages/api/export/[slug].ts
index 1b2451f..a933960 100644
--- a/apps/studio/src/pages/api/export/[slug].ts
+++ b/apps/studio/src/pages/api/export/[slug].ts
@@ -1,3 +1,4 @@
+import {serveApiDocumentation} from '../../../lib/api-documentation';
 import type {NextApiRequest,NextApiResponse} from 'next';
 import {ideas} from '../../../content/ideas';
-export default function handler(req:NextApiRequest,res:NextApiResponse){if(req.method!=='GET')return res.status(405).end();const idea=ideas.find(i=>i.slug===req.query.slug);if(!idea)return res.status(404).end();if(req.query.format==='markdown'){res.setHeader('Content-Type','text/markdown; charset=utf-8');return res.send('# '+idea.title+'\n\n'+idea.summary+'\n\n'+idea.slides.map(s=>'## '+s.heading+'\n\n'+s.body).join('\n\n'));}res.setHeader('Content-Disposition',`attachment; filename="${idea.slug}.json"`);return res.json({version:1,...idea});}
+export default function handler(req:NextApiRequest,res:NextApiResponse){if(serveApiDocumentation(req,res,'/studio/api/export/{slug}'))return;if(req.method!=='GET')return res.status(405).end();const idea=ideas.find(i=>i.slug===req.query.slug);if(!idea)return res.status(404).end();if(req.query.format==='markdown'){res.setHeader('Content-Type','text/markdown; charset=utf-8');return res.send('# '+idea.title+'\n\n'+idea.summary+'\n\n'+idea.slides.map(s=>'## '+s.heading+'\n\n'+s.body).join('\n\n'));}res.setHeader('Content-Disposition',`attachment; filename="${idea.slug}.json"`);return res.json({version:1,...idea});}
diff --git a/apps/studio/src/pages/api/health.ts b/apps/studio/src/pages/api/health.ts
index efeacca..4d52af9 100644
--- a/apps/studio/src/pages/api/health.ts
+++ b/apps/studio/src/pages/api/health.ts
@@ -1,2 +1,3 @@
+import {serveApiDocumentation} from '../../lib/api-documentation';
 import type {NextApiRequest,NextApiResponse} from "next";
-export default function handler(req:NextApiRequest,res:NextApiResponse){res.setHeader("Cache-Control","no-store");if(!["GET","HEAD"].includes(req.method||""))return res.status(405).end();return req.method==="HEAD"?res.status(200).end():res.status(200).json({status:"ok",service:"prompt-studio"});}
+export default function handler(req:NextApiRequest,res:NextApiResponse){if(serveApiDocumentation(req,res,'/studio/api/health'))return;res.setHeader("Cache-Control","no-store");if(!["GET","HEAD"].includes(req.method||""))return res.status(405).end();return req.method==="HEAD"?res.status(200).end():res.status(200).json({status:"ok",service:"prompt-studio"});}
diff --git a/apps/wiki/package.json b/apps/wiki/package.json
index 4ec54b4..01aa895 100644
--- a/apps/wiki/package.json
+++ b/apps/wiki/package.json
@@ -10,7 +10,7 @@
     "build": "next build && esbuild src/worker.ts --bundle --platform=node --format=cjs --external:pg-native --external:playwright-core --outfile=dist/worker.cjs && esbuild scripts/bootstrap.ts --bundle --platform=node --format=cjs --external:pg-native --external:playwright-core --outfile=dist/bootstrap.cjs && esbuild scripts/publish-learning-series.ts --bundle --platform=node --format=cjs --external:pg-native --external:playwright-core --outfile=dist/publish-learning-series.cjs && node scripts/prepare-standalone.mjs",
     "start": "next start",
     "typecheck": "next typegen && tsc --noEmit",
-    "test": "tsx --test tests/health.test.ts tests/model.test.ts tests/learning-series.test.ts tests/skill-docs.test.ts tests/wiki.test.ts tests/explore.test.ts tests/preview.test.ts tests/note-markdown.test.tsx",
+    "test": "tsx --test tests/api-documentation.test.ts tests/health.test.ts tests/model.test.ts tests/learning-series.test.ts tests/skill-docs.test.ts tests/wiki.test.ts tests/explore.test.ts tests/preview.test.ts tests/note-markdown.test.tsx",
     "test:smoke": "node scripts/smoke.mjs",
     "storage:prepare": "tsx scripts/bootstrap.ts",
     "content:publish-learning": "tsx scripts/publish-learning-series.ts",
diff --git a/apps/wiki/src/lib/api-documentation.ts b/apps/wiki/src/lib/api-documentation.ts
new file mode 100644
index 0000000..5921140
--- /dev/null
+++ b/apps/wiki/src/lib/api-documentation.ts
@@ -0,0 +1,101 @@
+import type {NextApiRequest,NextApiResponse} from 'next';
+
+// Read documentation before business validation or storage access. Mutations never enter this branch.
+export const apiDocuments:Record<string,readonly string[]>={
+  "/api/explore-feed": [
+    "统一内容流",
+    "GET",
+    "查询参数：q（可选，最多 200 字符）；category（可选，标签名称或命名空间）；cursor（可选，上一页 nextCursor）。",
+    "JSON：entries 数组与 nextCursor；没有更多结果时 nextCursor 为 null。静态内容仅出现在第一页。",
+    "GET /api/explore-feed?q=排版",
+    "503：素材库暂时无法连接。"
+  ],
+  "/api/feed": [
+    "素材列表",
+    "GET",
+    "查询参数：section（images / videos / audio / articles / motion，可选）；path（可选，标签 path）；q（可选，最多 200 字符）；cursor（可选，上一页 nextCursor）。",
+    "JSON：posts、tags、contributions、nextCursor；每页最多 24 个 post。",
+    "GET /api/feed?section=images",
+    "400：未知 section、标签或无效游标。"
+  ],
+  "/api/notes/{id}": [
+    "读取与编辑笔记",
+    "GET, PUT",
+    "路径参数：id，笔记稳定 ID。PUT 使用 application/json，所有字段必填：title（1–200 字符）、description（最多 1000 字符）、markdown（最多 100000 字符）、tags（最多 50 个标签 UUID）、revision（GET 返回的 entry.revision，64 位十六进制）。",
+    "GET 返回 {entry,tags}；PUT 返回更新后的 {entry}。先 GET 获取 revision，再 PUT；冲突后重新读取。",
+    "GET /api/notes/{id}\nPUT /api/notes/{id}\n{\"title\":\"标题\",\"description\":\"简介\",\"markdown\":\"正文\",\"tags\":[],\"revision\":\"<GET 返回的 entry.revision>\"}",
+    "400：输入错误；404：笔记不存在；409：版本冲突。"
+  ],
+  "/api/posts": [
+    "创建笔记或素材包",
+    "POST",
+    "application/json：kind（必填，image / video / audio / article / motion）、title（必填，1–200 字符）；slug（可选，最多 120 字符，以小写字母或数字开头，仅含小写字母、数字、连字符）；description（可选，最多 1000 字符）；text（可选，最多 100000 字符）；tags（可选，最多 50 个 UUID）；coverAssetId（可选，图片 UUID）；assets（可选，最多 100 项，{id: UUID,role: content | caption}，role 默认 content）。媒体类型必须引用至少一个对应类型的 content 素材。",
+    "201 JSON：{id,slug}。引用已有素材；不会在此接口上传二进制文件。",
+    "POST /api/posts\n{\"kind\":\"article\",\"title\":\"新笔记\",\"text\":\"正文\",\"tags\":[]}",
+    "400：输入或素材引用不合法；409：slug 已存在。"
+  ],
+  "/api/tags": [
+    "标签列表与创建",
+    "GET, POST",
+    "POST 使用 application/json：name（必填，去掉开头 # 并 trim 后 1–60 字符，不含 #、空白、英文或中文逗号）；slug（可选，最多 60 字符，以小写字母或数字开头，仅含小写字母、数字、连字符）。",
+    "GET 返回标签数组；POST 新建返回 201，名称已存在时复用并返回 200。标签含 id、name、slug、path。",
+    "POST /api/tags\n{\"name\":\"排版\"}",
+    "400：输入错误；409：slug 冲突。"
+  ],
+  "/api/upload": [
+    "上传媒体并创建素材包",
+    "POST",
+    "multipart/form-data：kind（必填，image / video / audio）；title（必填，1–200 字符）；slug（可选，小写字母或数字组成的非空段，以连字符分隔，最多 120 字符）；description（可选，最多 100000 字符）；tags（可选，UUID 数组的 JSON 字符串，最多 50 项）；文件字段名任意，至少一个文件。最多 16 个文件，单个不超过 250 MB，总计不超过 1 GB。图片支持 JPG、PNG、WebP、GIF、AVIF；音频必须为独立声音文件。",
+    "201 JSON：{id,slug,url,assets}，assets 为素材 UUID 数组。视频会自动进入后台加工队列。",
+    "POST /api/upload\nContent-Type: multipart/form-data\nkind=image\ntitle=示例图片\ntags=[]\nfile=<图片文件>",
+    "400：输入或媒体不合法；409：slug 冲突；413：上传超过限制。"
+  ],
+  "/api/media/{id}": [
+    "读取媒体原件或衍生文件",
+    "GET, HEAD",
+    "路径参数：id，素材 UUID。查询参数：variant（可选，poster / silent_video / audio_track，读取以 id 为来源的衍生素材）。支持 Range 请求头。",
+    "二进制媒体，Content-Type 随文件类型变化；200 为完整文件，206 为范围响应，HEAD 无正文。",
+    "GET /api/media/{id}?variant=poster",
+    "404：素材不存在或无效 variant；416：请求范围无效。"
+  ],
+  "/api/preview": [
+    "轻量图片预览",
+    "GET, HEAD",
+    "查询参数：source（必填，本站静态栅格图片路径，或 /api/media/<UUID>，可带 ?variant=poster；作为查询值时必须 URL 编码）；width（可选，240 / 480 / 960 / 1280，默认 480）。不接受任意远程图片地址。支持 If-None-Match。",
+    "WebP 图片；包含 ETag；缓存命中可返回 304；HEAD 无正文。",
+    "GET /api/preview?source=%2Fapi%2Fmedia%2F<UUID>&width=480",
+    "400：参数不合法；404：图片不存在；503：预览暂不可用。"
+  ],
+  "/api/skills/street-people": [
+    "透明人物规范与上传",
+    "GET, POST",
+    "GET 默认返回 JSON 规范，format=md 返回创作指导 Markdown。POST 使用 multipart/form-data，沿用 /api/upload 字段与大小限制；kind 固定为 image，title 默认“街头小人 · 新生成”。图片必须为带 alpha 的 PNG，含 alpha=0 的透明像素及 alpha≥250 的像素。",
+    "GET 返回生成规范；POST 返回 201 {id,slug,url,assets}。",
+    "GET /api/skills/street-people\nPOST /api/skills/street-people\nContent-Type: multipart/form-data\nfile=<透明 PNG>",
+    "400：图片或字段不合法；413：超过上传限制。"
+  ],
+  "/api/health": [
+    "应用健康检查",
+    "GET, HEAD",
+    "无业务参数。",
+    "GET 返回 JSON：status、service、release；HEAD 仅返回状态和响应头。",
+    "GET /api/health",
+    "405：不支持的方法。"
+  ],
+  "/api/ready": [
+    "依赖就绪检查",
+    "GET",
+    "无业务参数。检查 PostgreSQL 和对象存储桶。",
+    "200 JSON：{\"status\":\"ok\",\"database\":\"ready\",\"objects\":\"ready\"}。",
+    "GET /api/ready",
+    "503 JSON：{\"status\":\"unavailable\"}。"
+  ]
+};
+export function serveApiDocumentation(req:NextApiRequest,res:NextApiResponse,path:string){
+ if(!['GET','HEAD'].includes(req.method||'')||typeof req.query.agent_mode!=='string'||req.query.agent_mode.toLowerCase()!=='true')return false;
+ const doc=apiDocuments[path];if(!doc)return false;
+ const [title,methods,parameters,response,example,errors]=doc;
+ const text=`# ${title}\n\n地址：${path}\n方法：${methods}\n\n## 参数\n${parameters}\n\n## 响应\n${response}\n\n## 调用示例\n${example}\n\n## 错误\n${errors}\n\n## 读取说明\n使用 GET 或 HEAD，在原地址加 ?agent_mode=True；已有查询参数时加 &agent_mode=True。值不区分大小写。动态路径可使用实际 ID，也可保留占位符读取本接口说明。\n业务调用请移除 agent_mode。POST / PUT 不会被转换为说明请求。写入接口会拒绝 Origin 与 Host 不一致的请求；当前没有 API Key 或登录鉴权。\n\nAPI 目录：/api?agent_mode=True\n`;
+ res.setHeader('Content-Type','text/plain; charset=utf-8');res.setHeader('Cache-Control','no-store');
+ res.status(200);if(req.method==='HEAD')res.end();else res.send(text);return true;
+}
diff --git a/apps/wiki/src/pages/api/explore-feed.ts b/apps/wiki/src/pages/api/explore-feed.ts
index 549f9ae..d03c669 100644
--- a/apps/wiki/src/pages/api/explore-feed.ts
+++ b/apps/wiki/src/pages/api/explore-feed.ts
@@ -1,3 +1,5 @@
+import {serveApiDocumentation} from '@/lib/api-documentation';
 import type {NextApiRequest,NextApiResponse} from 'next';
 import {exploreFeed} from '@/lib/explore';
-export default async function handler(req:NextApiRequest,res:NextApiResponse){if(req.method!=='GET')return res.status(405).end();try{return res.json(await exploreFeed(String(req.query.q||'').slice(0,200),String(req.query.category||''),String(req.query.cursor||'')||undefined));}catch{return res.status(503).json({error:'素材库暂时无法连接'});}}
+export default async function handler(req:NextApiRequest,res:NextApiResponse){
+ if(serveApiDocumentation(req,res,'/api/explore-feed'))return;if(req.method!=='GET')return res.status(405).end();try{return res.json(await exploreFeed(String(req.query.q||'').slice(0,200),String(req.query.category||''),String(req.query.cursor||'')||undefined));}catch{return res.status(503).json({error:'素材库暂时无法连接'});}}
diff --git a/apps/wiki/src/pages/api/feed.ts b/apps/wiki/src/pages/api/feed.ts
index 115a3d1..1bac43d 100644
--- a/apps/wiki/src/pages/api/feed.ts
+++ b/apps/wiki/src/pages/api/feed.ts
@@ -1,8 +1,10 @@
+import {serveApiDocumentation} from '@/lib/api-documentation';
 import type { NextApiRequest,NextApiResponse } from "next";
 import { feed } from "@/lib/library";
 import { validSection } from "@/lib/model";
 import { apiError } from "@/lib/api";
 export default async function handler(req:NextApiRequest,res:NextApiResponse){
+ if(serveApiDocumentation(req,res,'/api/feed'))return;
  if(req.method!=='GET')return res.status(405).end();
  try {const section=String(req.query.section||'');if(section&&!validSection(section))return res.status(400).json({error:'未知分类'});
   res.setHeader('Cache-Control','no-store');return res.json(await feed({kind:validSection(section)?.kind,path:String(req.query.path||''),cursor:String(req.query.cursor||''),q:String(req.query.q||'').slice(0,200)}));
diff --git a/apps/wiki/src/pages/api/health.ts b/apps/wiki/src/pages/api/health.ts
index a8acc74..7f74171 100644
--- a/apps/wiki/src/pages/api/health.ts
+++ b/apps/wiki/src/pages/api/health.ts
@@ -1,7 +1,9 @@
+import {serveApiDocumentation} from '@/lib/api-documentation';
 import type { NextApiRequest, NextApiResponse } from "next";
 import { healthResponse } from "@/lib/health";
 
 export default function handler(req: NextApiRequest, res: NextApiResponse) {
+ if(serveApiDocumentation(req,res,'/api/health'))return;
   const { statusCode, body } = healthResponse(req.method, process.env.RELEASE_SHA);
   res.setHeader("Cache-Control", "no-store");
   if (statusCode === 405) res.setHeader("Allow", "GET, HEAD");
diff --git a/apps/wiki/src/pages/api/index.ts b/apps/wiki/src/pages/api/index.ts
new file mode 100644
index 0000000..5c5e7c4
--- /dev/null
+++ b/apps/wiki/src/pages/api/index.ts
@@ -0,0 +1,14 @@
+import type {NextApiRequest,NextApiResponse} from 'next';
+import {apiDocuments} from '@/lib/api-documentation';
+export default function handler(req:NextApiRequest,res:NextApiResponse){
+ if(!['GET','HEAD'].includes(req.method||'')){res.setHeader('Allow','GET, HEAD');return res.status(405).end();}
+ const entries=[...Object.entries(apiDocuments).map(([path,doc])=>({path,title:doc[0],methods:doc[1],documentation:path+'?agent_mode=True'})),
+ {path:'/studio/api/export/{slug}',title:'导出创作方案',methods:'GET',documentation:'/studio/api/export/{slug}?agent_mode=True'},
+ {path:'/studio/api/health',title:'创作站健康检查',methods:'GET, HEAD',documentation:'/studio/api/health?agent_mode=True'}];
+ res.setHeader('Cache-Control','no-store');
+ const plain=typeof req.query.agent_mode==='string'&&req.query.agent_mode.toLowerCase()==='true';
+ res.setHeader('Content-Type',plain?'text/plain; charset=utf-8':'application/json; charset=utf-8');
+ if(req.method==='HEAD')return res.status(200).end();
+ if(plain)return res.send('# PROMPT 业务 API\n\n各接口使用 GET + agent_mode=True 读取说明；已有参数时用 & 拼接。动态路径允许保留占位符。业务调用请移除该参数。\n\n'+entries.map(e=>`- ${e.title}（${e.methods}）：${e.documentation}`).join('\n')+'\n');
+ return res.json({entries});
+}
diff --git a/apps/wiki/src/pages/api/media/[id].ts b/apps/wiki/src/pages/api/media/[id].ts
index cbd56a2..0c2a8fc 100644
--- a/apps/wiki/src/pages/api/media/[id].ts
+++ b/apps/wiki/src/pages/api/media/[id].ts
@@ -1,8 +1,10 @@
+import {serveApiDocumentation} from '@/lib/api-documentation';
 import type { NextApiRequest,NextApiResponse } from "next";
 import type { Readable } from "node:stream";
 import { db } from "@/lib/db";
 import { getObject } from "@/lib/storage";
 export default async function handler(req:NextApiRequest,res:NextApiResponse){
+ if(serveApiDocumentation(req,res,'/api/media/{id}'))return;
  if(!['GET','HEAD'].includes(req.method||''))return res.status(405).end();
  if(!/^[0-9a-f-]{36}$/.test(String(req.query.id)))return res.status(404).end();
  try{
diff --git a/apps/wiki/src/pages/api/notes/[id].ts b/apps/wiki/src/pages/api/notes/[id].ts
index 652625c..f2266b1 100644
--- a/apps/wiki/src/pages/api/notes/[id].ts
+++ b/apps/wiki/src/pages/api/notes/[id].ts
@@ -1,9 +1,11 @@
+import {serveApiDocumentation} from '@/lib/api-documentation';
 import type {NextApiRequest,NextApiResponse} from 'next';
 import {getEntry} from '@/lib/explore';
 import {tags} from '@/lib/library';
 import {noteEditInput,saveNote,NoteEditConflict} from '@/lib/note-edits';
 import {sameOrigin,apiError} from '@/lib/api';
 export default async function handler(req:NextApiRequest,res:NextApiResponse){
+ if(serveApiDocumentation(req,res,'/api/notes/{id}'))return;
  res.setHeader('Cache-Control','no-store');
  if(!['GET','PUT'].includes(req.method||'')){res.setHeader('Allow','GET, PUT');return res.status(405).end();}
  try{
diff --git a/apps/wiki/src/pages/api/posts/index.ts b/apps/wiki/src/pages/api/posts/index.ts
index e2e14f3..3cea449 100644
--- a/apps/wiki/src/pages/api/posts/index.ts
+++ b/apps/wiki/src/pages/api/posts/index.ts
@@ -1,7 +1,9 @@
+import {serveApiDocumentation} from '@/lib/api-documentation';
 import type { NextApiRequest,NextApiResponse } from "next";
 import { createPost,postInput } from "@/lib/write";
 import { sameOrigin,apiError } from "@/lib/api";
 export default async function handler(req:NextApiRequest,res:NextApiResponse){
+ if(serveApiDocumentation(req,res,'/api/posts'))return;
  if(req.method!=='POST')return res.status(405).end();
  try{sameOrigin(req);return res.status(201).json(await createPost(postInput.parse(req.body)));}catch(e){return apiError(res,e);}
 }
diff --git a/apps/wiki/src/pages/api/preview.ts b/apps/wiki/src/pages/api/preview.ts
index df82861..0ea275c 100644
--- a/apps/wiki/src/pages/api/preview.ts
+++ b/apps/wiki/src/pages/api/preview.ts
@@ -1,6 +1,8 @@
+import {serveApiDocumentation} from '@/lib/api-documentation';
 import type {NextApiRequest,NextApiResponse} from 'next';
 import {db} from '@/lib/db';
 import {getObject} from '@/lib/storage';
 import {previewWidth,cachedPreview,loadStaticPreview} from '@/lib/preview';
-export default async function handler(req:NextApiRequest,res:NextApiResponse){if(!['GET','HEAD'].includes(req.method||''))return res.status(405).end();const width=previewWidth(req.query.width);if(!width||typeof req.query.source!=='string')return res.status(400).end();try{const source=req.query.source;let input:{identity:string;load:()=>Promise<Buffer>};if(source.startsWith('/api/media/')){const match=source.match(/^\/api\/media\/([0-9a-f-]{36})(?:\?variant=(poster))?$/);if(!match)return res.status(400).end();const result=match[2]?await db().query('SELECT storage_key,mime_type FROM assets WHERE source_asset_id=$1 AND derivation=$2',[match[1],match[2]]):await db().query('SELECT storage_key,mime_type FROM assets WHERE id=$1',[match[1]]);const row=result.rows[0];if(!row?.storage_key||!row.mime_type?.startsWith('image/'))return res.status(404).end();input={identity:row.storage_key,load:async()=>{const object=await getObject(row.storage_key);if((object.ContentLength||0)>64*1024*1024)throw Error('Image too large');const chunks:Buffer[]=[];let length=0;for await(const chunk of object.Body as AsyncIterable<Uint8Array>){length+=chunk.length;if(length>64*1024*1024)throw Error('Image too large');chunks.push(Buffer.from(chunk));}return Buffer.concat(chunks);}};}else input=await loadStaticPreview(source);const {bytes,etag}=await cachedPreview(input.identity,width,input.load);res.setHeader('ETag',etag);res.setHeader('Cache-Control','public, max-age=3600');res.setHeader('Content-Type','image/webp');res.setHeader('X-Content-Type-Options','nosniff');if(req.headers['if-none-match']===etag)return res.status(304).end();res.setHeader('Content-Length',bytes.length);return req.method==='HEAD'?res.end():res.send(bytes);}catch(e){const message=(e as Error).message;if(message.includes('Invalid source'))return res.status(400).end();if((e as NodeJS.ErrnoException).code==='ENOENT')return res.status(404).end();res.setHeader('Retry-After','5');return res.status(503).end();}}
+export default async function handler(req:NextApiRequest,res:NextApiResponse){
+ if(serveApiDocumentation(req,res,'/api/preview'))return;if(!['GET','HEAD'].includes(req.method||''))return res.status(405).end();const width=previewWidth(req.query.width);if(!width||typeof req.query.source!=='string')return res.status(400).end();try{const source=req.query.source;let input:{identity:string;load:()=>Promise<Buffer>};if(source.startsWith('/api/media/')){const match=source.match(/^\/api\/media\/([0-9a-f-]{36})(?:\?variant=(poster))?$/);if(!match)return res.status(400).end();const result=match[2]?await db().query('SELECT storage_key,mime_type FROM assets WHERE source_asset_id=$1 AND derivation=$2',[match[1],match[2]]):await db().query('SELECT storage_key,mime_type FROM assets WHERE id=$1',[match[1]]);const row=result.rows[0];if(!row?.storage_key||!row.mime_type?.startsWith('image/'))return res.status(404).end();input={identity:row.storage_key,load:async()=>{const object=await getObject(row.storage_key);if((object.ContentLength||0)>64*1024*1024)throw Error('Image too large');const chunks:Buffer[]=[];let length=0;for await(const chunk of object.Body as AsyncIterable<Uint8Array>){length+=chunk.length;if(length>64*1024*1024)throw Error('Image too large');chunks.push(Buffer.from(chunk));}return Buffer.concat(chunks);}};}else input=await loadStaticPreview(source);const {bytes,etag}=await cachedPreview(input.identity,width,input.load);res.setHeader('ETag',etag);res.setHeader('Cache-Control','public, max-age=3600');res.setHeader('Content-Type','image/webp');res.setHeader('X-Content-Type-Options','nosniff');if(req.headers['if-none-match']===etag)return res.status(304).end();res.setHeader('Content-Length',bytes.length);return req.method==='HEAD'?res.end():res.send(bytes);}catch(e){const message=(e as Error).message;if(message.includes('Invalid source'))return res.status(400).end();if((e as NodeJS.ErrnoException).code==='ENOENT')return res.status(404).end();res.setHeader('Retry-After','5');return res.status(503).end();}}
 export const config={api:{responseLimit:false}};
diff --git a/apps/wiki/src/pages/api/ready.ts b/apps/wiki/src/pages/api/ready.ts
index 6385d5e..59d9b63 100644
--- a/apps/wiki/src/pages/api/ready.ts
+++ b/apps/wiki/src/pages/api/ready.ts
@@ -1,8 +1,10 @@
+import {serveApiDocumentation} from '@/lib/api-documentation';
 import type { NextApiRequest,NextApiResponse } from 'next';
 import { db } from '@/lib/db';
 import { storage,bucket } from '@/lib/storage';
 import { HeadBucketCommand } from '@aws-sdk/client-s3';
 export default async function handler(req:NextApiRequest,res:NextApiResponse){
+ if(serveApiDocumentation(req,res,'/api/ready'))return;
  if(req.method!=='GET')return res.status(405).end();
  res.setHeader('Cache-Control','no-store');
  try{await db().query('SELECT 1 FROM schema_migrations LIMIT 1');await storage().send(new HeadBucketCommand({Bucket:bucket()}));return res.json({status:'ok',database:'ready',objects:'ready'});}catch{return res.status(503).json({status:'unavailable'});}
diff --git a/apps/wiki/src/pages/api/skills/street-people.ts b/apps/wiki/src/pages/api/skills/street-people.ts
index 1bbe1d7..293f17f 100644
--- a/apps/wiki/src/pages/api/skills/street-people.ts
+++ b/apps/wiki/src/pages/api/skills/street-people.ts
@@ -1,3 +1,4 @@
+import {serveApiDocumentation} from '@/lib/api-documentation';
 import type {NextApiRequest,NextApiResponse} from "next";
 import {upload} from "../upload";
 import {streetPeople} from "@/lib/street-people";
@@ -5,6 +6,7 @@ import {guidanceMarkdown} from "@/content/skills/guidance";
 import {validateCharacter} from "@/lib/character-image";
 export const config={api:{bodyParser:false}};
 export default async function handler(req:NextApiRequest,res:NextApiResponse){
+ if(serveApiDocumentation(req,res,'/api/skills/street-people'))return;
  res.setHeader("Allow","GET, POST");
  if(req.method==="GET"){
   res.setHeader("Cache-Control","public, max-age=300");
diff --git a/apps/wiki/src/pages/api/tags.ts b/apps/wiki/src/pages/api/tags.ts
index b1cb376..a232884 100644
--- a/apps/wiki/src/pages/api/tags.ts
+++ b/apps/wiki/src/pages/api/tags.ts
@@ -1,3 +1,4 @@
+import {serveApiDocumentation} from '@/lib/api-documentation';
 import type {NextApiRequest,NextApiResponse} from 'next';
 import {randomUUID} from 'node:crypto';
 import {z} from 'zod';
@@ -5,6 +6,7 @@ import {db} from '@/lib/db';
 import {tags} from '@/lib/library';
 import {sameOrigin,apiError} from '@/lib/api';
 export default async function handler(req:NextApiRequest,res:NextApiResponse){
+ if(serveApiDocumentation(req,res,'/api/tags'))return;
  try{
   if(req.method==='GET')return res.json(await tags());
   if(req.method!=='POST')return res.status(405).end();
diff --git a/apps/wiki/src/pages/api/upload.ts b/apps/wiki/src/pages/api/upload.ts
index fe2715f..02bc364 100644
--- a/apps/wiki/src/pages/api/upload.ts
+++ b/apps/wiki/src/pages/api/upload.ts
@@ -1,3 +1,4 @@
+import {serveApiDocumentation} from '@/lib/api-documentation';
 import type { NextApiRequest,NextApiResponse } from "next";
 import formidable,{type File} from "formidable";
 import { randomUUID,createHash } from "node:crypto";
@@ -12,6 +13,7 @@ import { sameOrigin,apiError } from "@/lib/api";
 export const config={api:{bodyParser:false}};
 export type UploadPolicy = { validateImage?: (path:string) => Promise<void>; defaultTitle?:string };
 export async function upload(req:NextApiRequest,res:NextApiResponse,policy:UploadPolicy={}){
+ if(serveApiDocumentation(req,res,'/api/upload'))return;
  if(req.method!=='POST')return res.status(405).end();
  const temporary:string[]=[];const uploaded:string[]=[];
  try{
diff --git a/apps/wiki/tests/api-documentation.test.ts b/apps/wiki/tests/api-documentation.test.ts
new file mode 100644
index 0000000..9acb48e
--- /dev/null
+++ b/apps/wiki/tests/api-documentation.test.ts
@@ -0,0 +1,55 @@
+import assert from 'node:assert/strict';
+import {test} from 'node:test';
+import type {NextApiRequest,NextApiResponse} from 'next';
+import {apiDocuments,serveApiDocumentation} from '../src/lib/api-documentation';
+import index from '../src/pages/api/index';
+
+function response(){
+ const state={status:0,headers:{} as Record<string,string>,body:undefined as unknown};
+ const res={setHeader(name:string,value:string){state.headers[name]=value;return res;},status(code:number){state.status=code;return res;},send(body:unknown){state.body=body;return res;},json(body:unknown){state.body=body;return res;},end(){return res;}};
+ return {state,res:res as unknown as NextApiResponse};
+}
+const request=(method:string,agent_mode:unknown)=>({method,query:{agent_mode}} as unknown as NextApiRequest);
+
+test('every business handler serves documentation before validating parameters or accessing dependencies',async()=>{
+ const routes:Record<string,string>={
+ '/api/explore-feed':'explore-feed','/api/feed':'feed','/api/notes/{id}':'notes/[id]',
+ '/api/posts':'posts/index','/api/tags':'tags','/api/upload':'upload',
+ '/api/media/{id}':'media/[id]','/api/preview':'preview',
+ '/api/skills/street-people':'skills/street-people','/api/health':'health','/api/ready':'ready',
+ };
+ for(const [path,route] of Object.entries(routes)){
+  const {default:handler}=await import('../src/pages/api/'+route+'.ts');
+  for(const method of ['GET','HEAD']){
+   const {state,res}=response();
+   await handler(request(method,'tRuE'),res);
+   assert.equal(state.status,200,path);
+   assert.equal(state.headers['Content-Type'],'text/plain; charset=utf-8',path);
+   if(method==='HEAD')assert.equal(state.body,undefined);else {
+    assert.ok(String(state.body).includes(path),path);
+    assert.ok(String(state.body).includes('参数'),path);
+   }
+  }
+ }
+ assert.deepEqual(Object.keys(routes).sort(),Object.keys(apiDocuments).sort());
+});
+
+test('normal calls and mutations do not enter documentation mode',()=>{
+ for(const [method,value] of [['GET',undefined],['GET','false'],['GET',['True','false']],['POST','True'],['PUT','True'],['DELETE','True']]){
+  const {state,res}=response();
+  assert.equal(serveApiDocumentation(request(method as string,value),res,'/api/posts'),false);
+  assert.equal(state.status,0);
+ }
+});
+
+test('index exposes every business endpoint and its text URL',()=>{
+ const {state,res}=response();index(request('GET','True'),res);
+ for(const path of [...Object.keys(apiDocuments),'/studio/api/export/{slug}','/studio/api/health'])assert.ok(String(state.body).includes(path+'?agent_mode=True'));
+});
+
+test('health keeps its regular JSON response',async()=>{
+ const {default:handler}=await import('../src/pages/api/health');
+ const {state,res}=response();handler(request('GET',undefined),res);
+ assert.equal(state.status,200);assert.equal((state.body as {status:string}).status,'ok');
+});
+
diff --git a/docs/api.md b/docs/api.md
new file mode 100644
index 0000000..1e80d53
--- /dev/null
+++ b/docs/api.md
@@ -0,0 +1,16 @@
+# 业务 API 说明
+
+业务 API 目录：`/api`（JSON）或 `/api?agent_mode=True`（纯文本）。
+
+每个业务接口都使用原路径加 `agent_mode=True` 返回 `text/plain; charset=utf-8` 的接口说明，包含用途、方法、参数、响应、调用示例和错误。查询值不区分大小写；已有查询参数时使用 `&agent_mode=True`。使用 GET 或 HEAD 读取说明，HEAD 不含正文；说明不查询数据库或对象存储，不要求动态 ID 实际存在。
+
+例如：
+
+- `/api/upload?agent_mode=True`
+- `/api/notes/{id}?agent_mode=True`
+- `/api/preview?source=%2Fexample.png&agent_mode=True`
+- `/studio/api/export/{slug}?agent_mode=True`
+
+业务调用时移除该参数。POST、PUT 等写入方法保持原有行为，不会因该参数变成文档请求。页面正文和 Markdown 兼容接口继续使用原有规则。
+
+Wiki 文档注册表位于 `apps/wiki/src/lib/api-documentation.ts`，由各业务路由在 handler 开头调用；目录从同一注册表生成。Studio 文档位于 `apps/studio/src/lib/api-documentation.ts`，随创作站独立部署。